Cardiovascular surgery is a frequent and effective choice for treatment of cardiovascular disease, with over 570,000 coronary bypass operations each year alone. Clamping or ligation is used to occlude blood flow, a practice which causes injury to the endothelium of the vessel and exposes the patient to complications including thrombosis and atherosclerosis leading to stenosis. This project involves using magnetic microparticle technology to occlude blood flow during surgery, thus avoiding vessel injury. This will be accomplished by: 1) developing new magnetic microparticles with a range of diameters and magnetic properties; 2) characterizing the properties of the microparticles; and 3) testing the microparticles for ability to occlude flow in vitro under conditions of flow, pressure, and fluid composition encompassing those in the vasculature. An apparatus will be constructed to study flow occlusion in a closed system maintainable at constant pressure. Microparticles producing acceptable occlusion will be chosen for future study, with the long- term goal of developing a technology to replace clamping, thereby improving surgical outcome. PROPOSED COMMERCIAL APPLICATIONS: A novel method for occluding blood flow during surgery that would replace traditional clamping or ligation in many situations would have tremendous commercial impact. The potential market could include surgeons in almost every sub specialty, including especially cardiology, vascular surgery, general surgery, surgical oncology, and transplantation.